For instance, in an area in which an inundation may occur due to a tsunami or a flood caused by an earthquake or the like, an infiltration or an outflow of water has been generally prevented by raising the soil foundations of a building or by building levees on the both banks of a river.
Around a building in which the soil foundations cannot be raised, a tide plate is generally installed at the location in which a water flow must be cut off, and the water is kept back by the tide plate.
A conventional tide plate of this kind is generally formed in any shape such as a flat plate, and is installed manually in advance at the location in which water must be kept back in the case in which overhead flooding may occur.
Moreover, a tide apparatus in which a tide plate powered by electricity can be moved up and down has also been developed. The sensor of the tide apparatus detects the time when the tide plate must be installed in overhead flooding or the like, and water is kept back by automatically raising the tide plate based on a signal output from the sensor.
However, in the case in which the soil foundations of a building are raised, a staircase must be formed for going in and out of the building, thereby resulting in inconvenience in utilizing the building.
Moreover, in the case in which a tide plate is installed manually, the prediction of a flood does not come true in some cases and the installation of the tide plate is futile. In the case in which heavy rain occurs suddenly and hands are insufficient, the tide plate cannot be installed. In addition, an installation of the tide plate may prevent a person from going in and out in some cases.
That is to say, it is preferable that the tide plate is normally housed in a separate site such as under the soil foundation face in such a manner that the tide plate does not obstruct the entrance and exit or the passage, thereby improving a convenience in utilizing the building.
Unfortunately, in the case in which the tide plate is powered by electricity to be moved up and down, the tide plate does not operate by a failure or a power outage in some cases, and an installation cost becomes extremely high.
Therefore, a tide apparatus 100 shown in FIG. 28 as disclosed in Patent document 1 (Japanese Patent Application Laid-Open Publication No. 7-197751) has been proposed as a tide apparatus for automatically installing the tide plate in order to keep back water in overhead flooding or the like without utilizing power such as human power and electricity.
The tide apparatus 100 contains an underground pit 102 formed under a soil foundation face 110, a water inflow port 106 and a slit 108 that vertically penetrate into a ceiling wall 104 of the underground pit 102, and a tide plate 112 that is linked to a floating member 114 at the bottom end of the tide plate in the underground pit 102 for floating together with the floating member 114 by a buoyancy of water and that can protrude upward from the soil foundation face 110 through the slit 108.
For the tide apparatus 100, in the case in which overhead flooding occurs on the ground due to a flood caused by a heavy rain, water flows and gathers into the underground pit 102 from the water inflow port formed in the ceiling wall 104 of the underground pit 102. A buoyancy of the water that has gathered inside is then applied to the floating member 114, and the tide plate 112 rises together with the floating member 114 and protrudes upward from the soil foundation face 110, thereby keeping back water.
Patent document 2 (Japanese Patent Application Laid-Open Publication No. 2000-319857) discloses a tide apparatus 200 as shown in FIG. 29, in which an underground pit 202 is formed under a soil foundation face, a water inflow port 206 and a tide plate operation opening 208 that vertically penetrate into a ceiling wall 204 of the underground pit 202 are formed, the tide plate 210 is rotatably mounted in a pivoting manner to one end of the tide plate operation opening 208, and a floating member 214 located in the underground pit 202 is linked to a surface 212 on the underground pit 202 side of the tide plate 210 via the tide plate operation opening 208. A buoyancy of water raises the floating member 214 and rotates the tide plate 210, thereby installing the tide plate 210 in a standing manner above the soil foundation face.
Patent document 1: Japanese Patent Application Laid-Open Publication No. 7-197751
Patent document 2: Japanese Patent Application Laid-Open Publication No. 2000-319857
However, in the case in which no water flows into the underground pit 102 or 202 via the inflow port 106 or 206 in practice for such conventional tide apparatuses 100 and 200, the tide plate L12 or 210 cannot be installed in a standing manner above the soil foundation face.
That is to say, in the case in which no overhead flooding occurs on the ground due to a flood or the like, the tide apparatuses 100 and 200 are not operated.
In the case in which an outflow of water occurs due to a collapse of a levee or a tsunami caused by an earthquake, water does not gradually flood on the soil foundation face but a large amount of water flows once and for all in many cases. In this case, the operation of the tide apparatus is not useful for keeping back water.
Moreover, for the tide apparatus in accordance with the conventional art, in the case in which water flows into the underground pit, the tide plate protrudes upward from the soil foundation face. Consequently, even in the case in which drainage is slow in a normal rainfall, the tide plate operates, thereby obstructing the passage in some cases.
Once the tide plate is installed in a standing manner above the soil foundation face, the installing condition in a standing manner is maintained until the drainage of water in the underground pit is completed. Consequently, the tide plate obstructs the passage in the case in which a disaster occurs. For instance, an emergency vehicle cannot pass and rescue is delayed in some cases.
The present invention was made in consideration of such conditions, and an object of the present invention is to provide a tide apparatus for automatically installing the tide plate in order to reliably keep back water in overhead flooding or the like without depending on power such as human power and electricity and for installing the tide plate in advance in order to reliably keep back water in overhead flooding or the like even in the case in which a large amount of water flows once and for all due to a collapse of a levee or a tsunami caused by an earthquake.
Another object of the present invention is to provide a tide apparatus in which the tide plate is not operated in the case of a normal rainfall to prevent the passage from being obstructed.
Another object of the present invention is to provide a tide apparatus in which the tide plate that has protruded upward from the soil foundation face can be immediately drawn below the soil foundation face, thereby preventing the passage from being obstructed in the case in which a disaster occurs.